Swash-plate-type variable displacement compressor

ABSTRACT

A swash-plate-type variable displacement compressor is provided with a rotationally-driven drive shaft, a lug plate integrally fixed to the drive shaft, a swash plate fixed in a manner capable of being variably inclined to the drive shaft, a link mechanism for coupling the lug plate and the swash plate while permitting the variable inclination; and an actuator which is arranged between the lug plate and the swash plate and which uses pressure to change an inclination angle of the swash plate. The actuator has a cylindrical member which extends from a surface of the lug plate toward the swash plate, a bottomed cylindrical member fitted capable of being relatively displaceable to an outer peripheral surface of the cylindrical member, and a coil spring which is arranged in an inner space of the actuator, and which biases the bottomed cylindrical member in a direction which is away from the lug plate.

TECHNICAL FIELD

The present invention relates to a swash-plate-type variable displacement compressor for compressing a compressible fluid.

BACKGROUND ART

A swash-plate-type variable displacement compressor is provided with a drive shaft, a lug plate integrally rotating with the drive shaft, a swash plate fixed in a manner capable of being variably inclined to the drive shaft, a link mechanism for coupling the lug plate and the swash plate, an actuator for causing the swash plate to variably incline, pistons reciprocated by the swash plate, and a cylinder block to which the pistons are inserted and fitted. As an example of the actuator capable of achieving a short axis of the swash-plate-type variable displacement compressor, there has been proposed a technique in which a sleeve (movable body) is reciprocatably fixed to the drive shaft positioned between the lug plate and the swash plate, a circumferential groove in which one end of the sleeve is fitted to a surface of the lug plate is formed, and an enclosed space formed therebetween is a cylinder chamber, as disclosed in JP 2015-86793 A (Patent Document 1).

REFERENCE DOCUMENT LIST Patent Document

Patent Document 1: JP 2015-86793 A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

When starting a swash-plate-type variable displacement compressor, in order to reduce start-up torque, minimizing the inclination angle of the swash plate is desirable. As a mechanism for minimizing the inclination angle of the swash plate when the swash-plate-type variable displacement compressor is not in operation, a spring for biasing the sleeve in a direction which is away from the lug plate can be arranged, for example. However, since the capacity of the cylinder chamber is small in the swash-plate-type variable displacement compressor disclosed in Patent Document 1, the spring cannot be arranged in the cylinder chamber, and thus, it was difficult to reduce the start-up torque.

Thus, an object of the present invention is to provide a swash-plate-type variable displacement compressor which enables to reduce the start-up torque.

Means for Solving the Problem

Thus, the swash-plate-type variable displacement compressor comprises: a rotationally-driven drive shaft; a lug plate integrally fixed to the drive shaft; a swash plate fixed in a manner capable of being variably inclined to the drive shaft; a coupling mechanism for coupling the lug plate and the swash plate while permitting variable inclination of the swash plate, and an actuator which is arranged between the lug plate and the swash plate and which uses pressure to change an inclination angle of the swash plate. The actuator has a cylindrical member which extends from a surface of the lug plate toward the swash plate, a bottomed cylindrical member fitted capable of being relatively displaceable to an outer peripheral surface of the cylindrical member, and a biasing member which is arranged in an inner space defined by the lug plate, the cylindrical member and the bottomed cylindrical member, and which biases the bottomed cylindrical member in a direction which is away from the lug plate.

Effects of the Invention

According to the present invention, the start-up torque can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an example of a swash-plate-type variable displacement compressor.

FIG. 2 is a perspective view illustrating the details of the swash plate.

FIG. 3 illustrates the maximum inclination angle of the swash plate.

FIG. 4 illustrates the minimum inclination angle of the swash plate.

FIG. 5 illustrates a method for securing air tightness of the actuator.

FIG. 6 is a partial sectional view illustrating another example of the swash-plate-type variable displacement compressor.

FIG. 7 illustrates another method for securing air tightness of the actuator.

MODE FOR CARRYING OUT THE INVENTION

An embodiment for implementing the present invention will be described in detail below with reference to attached drawings.

FIG. 1 is an example of a swash-plate-type variable displacement compressor.

The swash-plate-type variable displacement compressor 100 is provided with a housing 150, a drive shaft 200, a lug plate 250, a swash plate 300, a link mechanism 350, an actuator 400, a plurality of pistons 450, and a control mechanism 500. Here, the link mechanism 350 is given as an example of the coupling mechanism.

The housing 150 has a front housing 160, a cylinder block 170, a valve unit 180, and a rear housing 190 which are detachably fastened through fasteners such as bolts.

The front housing 160 is in the stepped cylindrical shape having a larger diameter portion 162 and a smaller diameter portion 164, and is reduced in diameter in two stages as it departs from the cylinder block 170. Here, the degree of the cylindrical shape can be the cylindrical shape that can be recognized visually, and the reinforcing rib and the attaching boss, for example, may be formed on the outer peripheral surface (as for the shape, the same applies hereafter). Additionally, a wall 162A in the thin-plate circular shape which is positioned in the innermost portion of the larger diameter portion 162 protrudes toward the central portion than the inner peripheral surface of the smaller diameter portion 164, and here, rotatably supports the drive shaft 200. Furthermore, a suction port 162B for drawing the gaseous refrigerant from the low-pressure side of the refrigerant circuit is formed in the peripheral wall of the larger diameter portion 162. The pulley to which the driving force from the engine (not illustrated) is transmitted is mounted on the outer peripheral surface of the smaller diameter portion 164, and the rotation from the engine is connected to the drive shaft 200 through the electromagnetic clutch or torque limiter (not illustrated).

The cylinder block 170 is in the columnar shape having the same diameter as the larger diameter portion 162 of the front housing 160, and occludes the open end of the larger diameter portion 162. Therefore, a columnar shaped crank chamber 166 for accommodating at least the lug plate 250, the swash plate 300, the link mechanism 350 and the actuator 400 is formed in the inside of the larger diameter portion 162 of the front housing 160. Additionally, a plurality of cylinder bores 172 to which the plurality of pistons 450 is reciprocatably inserted and fitted is formed in the cylinder block 170. The cylinder bores 172 are, for example, formed around the shaft center of the cylinder block 170 equiangularly, and are penetrated from one end surface to the other end surface in the axial direction. Furthermore, a plurality of through holes 174 which extends in the axial direction in a predetermined position adjacent to each cylinder bore 172 is formed in the cylinder block 170.

In the center portion of the cylinder block 170, there is formed a through hole 176 in a stepped columnar shape which is reduced in diameter in three stages as it departs from the front housing 160. The smaller diameter portion of the through hole 176 at least has the inner diameter in which the drive shaft 200 is movable in the axial direction.

The valve unit 180 is in the thin-plate disc shape having the same diameter as the cylinder block 170, and is held between the cylinder block 170 and the rear housing 190. A suction hole 180A for drawing the gaseous refrigerant to the cylinder bores 172, and a discharging hole 180B for discharging the gaseous refrigerant from the cylinder bores 172 are respectively formed on a plate surface of the valve unit 180, at the position facing the cylinder bores 172 of the cylinder block 170. Additionally, in the center portion of the valve unit 180, there is formed a through hole 180C having the same diameter as the smaller diameter portion of the through hole 176 which is formed in the center portion of the cylinder block 170.

Furthermore, a through hole 180D having the same diameter as the through holes 174 is formed on the plate surface of the valve unit 180, at the position facing the through holes 174 of the cylinder block 170. Still further, a suction reed valve 182 which is open at the time of drawing the gaseous refrigerant to the cylinder bores 172 through the suction hole 180A, and a discharge reed valve 184 which is open at the time of discharging the gaseous refrigerant from the cylinder bores 172 through the discharging hole 180B are respectively attached at a predetermined position of the plate surface of the valve unit 180.

The rear housing 190 is in the columnar shape having the same diameter as the valve unit 180, and is fastened to the cylinder block 170 through the valve unit 180. A plurality of suction chambers 192 is formed on one end surface in the axial direction of the rear housing 190, that is, on the end surface which is the fastening surface to the valve unit 180, which at the position facing the suction hole 180A and the position facing the through hole 180D of the valve unit 180. Additionally, a plurality of discharge chambers 194 is formed on one end surface in the axial direction of the rear housing 190, at the position facing the discharging hole 180B of the valve unit 180. Furthermore, a pressure adjustment chamber 196 for adjusting the pressure for causing the actuator 400 to operate is formed on one end surface in the axial direction of the rear housing 190, at the position facing the through hole 180C of the valve unit 180. Still further, the discharge port (not illustrated) for discharging the gaseous refrigerant from the discharge chambers 194 to the high-pressure side of the refrigerant circuit is formed in the rear housing 190.

The drive shaft 200 is attached around the shaft center of the housing 150 to allow rotation. Specifically, one end in the axial direction of the drive shaft 200 is rotatably supported to the wall 162A of the front housing 160 through the slide bearing 550. Another end in the axial direction of the drive shaft 200 is rotatably supported to the middle diameter portion of the through hole 176 formed in the cylinder block 170 through the slide bearing 560. Additionally, a known sealing device 570 for securing air tightness of the inner space of the housing 150 is arranged between the smaller diameter portion 164 of the front housing 160 and the drive shaft 200. Furthermore, in the drive shaft 200, there is formed a shaft hole 200A in the L-shaped passage that extends from the end surface of the other end in the axial direction of the drive shaft 200 along the shaft center and opens to the inner space of the later-described actuator 400.

The lug plate 250 is disc shaped in plan view, and at the center portion of the lug plate 250, there is formed a through hole 250A through which the drive shaft 200 is penetrated. The lug plate 250 is integrally fixed to the drive shaft 200 through the press-fit or key, for example. A thrust plate 580 in the thin-plate disc shape for supporting the thrust force of the lug plate 250 is arranged between one end surface in the axial direction of the lug plate 250 and the wall 162A of the front housing 160. Additionally, a cylindrical portion 250B in the cylindrical shape which vertically stands along the drive shaft 200 is integrally formed on the other end surface in the axial direction of the lug plate 250.

The swash plate 300 is in the disc shape in plan view, and at the center portion of the swash plate 300, there is formed a through hole 300A through which a part of the drive shaft 200 and actuator 400 are penetrated. The swash plate 300 is fixed in the position distant by a predetermined distance from the lug plate 250 in a manner capable of being variably inclined to the drive shaft 200. Here, the through hole 300A of the swash plate 300 has the first inner peripheral surface which comes into contact with the actuator 400 when the inclination angle to the drive shaft 200 is minimum, and the second inner peripheral surface which comes into contact with the actuator 400 when the inclination angle to the drive shaft 200 is maximum. Accordingly, the inclination angle to the drive shaft 200 is restricted by the first inner peripheral surface and second inner peripheral surface of the through hole 300A in the swash plate 300.

Additionally, as illustrated in FIG. 2, a circular recessed portion 300B with which the shoulder portion of the actuator 400 is locked is formed on one end surface in the axial direction of the swash plate 300. The recessed portion 300B of the swash plate 300 has the first locking surface with which the shoulder portion of the actuator 400 is locked when the inclination angle to the drive shaft 200 is minimum, and the second locking surface with which the shoulder portion of the actuator 400 is locked when the inclination angle to the drive shaft 200 is maximum. Therefore, the swash plate 300 can be variably inclined without interference with the actuator 400 within the minimum to maximum range of the inclination angle to the drive shaft 200.

The link mechanism 350 couples the lug plate 250 with the swash plate 300 while permitting variable inclination of the swash plate 300. Specifically, the link mechanism 350 has a first member 360 which stands oblique outer side from the other end surface in the axial direction of the lug plate 250, a second member 370 which stands from one end surface in the axial direction of the swash plate 300 toward the lug plate 250, and a third member 380 for coupling the tip portion of the first member 360 and the tip portion of the second member 370 so as to be capable of being relatively displaceable to each other. Therefore, the link mechanism 350 transmits the rotational force of the lug plate 250 that integrally rotates with the drive shaft 200 to the swash plate 300. Additionally, the link mechanism 350 permits variable inclination of the swash plate 300 by changing of the relative angle of the third member 380 to the first member 360 and second member 370. The link mechanism 350 is not limited to the structure described above but can be any known link mechanism which is used in the swash-plate-type variable displacement compressor.

The actuator 400 which is arranged concentrically with the drive shaft 200 between the lug plate 250 and the swash plate 300 uses pressure to change the inclination angle of the swash plate 300. Specifically, the actuator 400 has a cylindrical member 410 fitted to the outer peripheral surface of the cylindrical portion 250B of the lug plate 250, a bottomed cylindrical member 420 fitted to the outer peripheral surface of the cylindrical member 410 so as to be capable of being relatively displaceable to each other, and a coil spring 430 which is arranged in the inner space defined by the lug plate 250, the cylindrical member 410 and the bottomed cylindrical member 420. Here, the coil spring 430 is given as an example of the biasing member.

The distance between the outer peripheral surface of the cylindrical member 410 and the inner peripheral surface of the bottomed cylindrical member 420 is set to the extent that the air tightness of the inner space of the actuator 400 can be secured within the limit that the bottomed cylindrical member 420 is capable of being relatively displaceable with respect to the cylindrical member 410. Additionally, the cylindrical member 410 may extend from the other end surface in the axial direction of the lug plate 250 toward the swash plate 300, and may be integrated with the lug plate 250, for example.

A through hole 420A through which the drive shaft 200 is penetrated is formed in the base plate of the bottomed cylindrical member 420. Additionally, a smaller diameter portion 420B in the cylindrical shape which extends from the periphery of the through hole 420A toward the swash plate 300 and is sandwiched between the through hole 300A of the swash plate 300 and the outer peripheral surface of the drive shaft 200 is formed on the outer surface of the base plate of the bottomed cylindrical member 420. Therefore, the bottomed cylindrical member 420 is in the stepped cylindrical shape having a smaller diameter portion 420B which is fitted so as to be capable of being relatively displaceable with respect to the outer peripheral surface of the drive shaft 200. The distance between the smaller diameter portion 420B of the bottomed cylindrical member 420 and outer peripheral surface of the drive shaft 200 is set to the extent that the air tightness of the inner space of the actuator 400 can be secured within the limit that the bottomed cylindrical member 420 is capable of being relatively displaceable with respect to the drive shaft 200. The coil spring 430 biases the bottomed cylindrical member 420 in the direction which is away from the lug plate 250. Instead of the coil spring 430, a known elastic member such as a rubber can be used, for example.

The pistons 450 are reciprocatably inserted and fitted in the cylinder bores 172 formed in the cylinder block 170. The proximal end portions of the pistons 450, that is, the end portions facing the crank chamber 166 are coupled to the swash plate 300 through a shoe 590 fixed to the peripheral edge of the swash plate 300. Therefore, when the drive shaft 200 rotates in a state in which the swash plate 300 is variably inclined, the shoe 590 converts the rotation into the reciprocating linear motion so that the pistons 450 are reciprocated with respect to the cylinder bores 172. Accordingly, the capacity of the compression chamber 178 defined by the cylinder bores 172, the valve unit 180 and the pistons 450 is increased and decreased so that the gaseous refrigerant is drawn and compressed in the compression chamber 178.

The control mechanism 500 has a low-pressure passage 510 which communicates between the suction chamber 192 and the pressure adjustment chamber 196 of the rear housing 190, a high-pressure passage 520 which communicates between the discharge chamber 194 and the pressure adjustment chamber 196 of the rear housing 190, a control valve 530 which is arranged in the low-pressure passage 510, and an orifice 540 which is arranged in the high-pressure passage 520. Here, the low-pressure passage 510, the high-pressure passage 520, the control valve 530 and the orifice 540 can be incorporated in the rear housing 190 but can also be arranged outside the rear housing 190.

The flow rate control valve that the opening degree is gradually reduced as the pressure increases in the suction chamber 192 can be used as the control valve 530. Therefore, the control mechanism 500 fully opens the low-pressure passage 510 when the pressure in the suction chamber 192 is equal to or lower than the lower limit value, and puts back the pressure in the pressure adjustment chamber 196 to the suction chamber 192 to lower the pressure. Additionally, the control mechanism 500 shuts the low-pressure passage 510 when the pressure in the suction chamber 192 is equal to or greater than the upper limit value to supply the pressure in the discharge chamber 194 to the pressure adjustment chamber 196. Furthermore, when the pressure in the suction chamber 192 is greater than the lower limit value and less than the upper limit value, the control mechanism 500 opens the low-pressure passage 510 at a medium opening degree to control the pressure in the pressure adjustment chamber 196 at medium pressure.

In the swash-plate-type variable displacement compressor 100 illustrated in FIG. 1, a pair of O-rings 600, for example, for securing air tightness between the drive shaft 200 and the cylinder block 170 is arranged between the other end in the axial direction of the drive shaft 200 and the smaller diameter portion of the through hole 176 of the cylinder block 170. Additionally, a coil spring 610 for pressing the swash plate 300 toward the lug plate 250 is arranged in the larger diameter portion of the through hole 176 of the cylinder block 170.

Next, the action of such swash-plate-type variable displacement compressor 100 is described.

When the drive shaft 200 is rotated by the engine or the electric motor, and the like, the lug plate 250 which is integrally fixed to the drive shaft 200 is rotated. The rotation of the lug plate 250 is transmitted to the swash plate 300 through the link mechanism 350 to rotate the swash plate 300. When the swash plate 300 rotates, the pistons 450 reciprocate with strokes according to the inclination angle of the swash plate 300. When the reciprocation of the pistons 450 increases the capacity of the compression chamber 178, the gaseous refrigerant drawn from the low-pressure side of the refrigerant circuit to the crank chamber 166 is introduced to the suction chamber 192 through the through holes 174 of the cylinder block 170 and the through hole 180D of the valve unit 180. The gaseous refrigerant introduced to the suction chamber 192 is introduced to the compression chamber 178 through the suction hole 180A and the suction reed valve 182 of the valve unit 180.

When the reciprocation of the pistons 450 decreases the capacity of the compression chamber 178, the capacity of the gaseous refrigerant introduced to the compression chamber 178 is decreased and compressed. When the pressure in the compression chamber 178 rises to a certain extent, the gaseous refrigerant is introduced to the discharge chamber 194 through the discharging hole 180B and the discharge reed valve 184 of the valve unit 180, and from here, discharged to the high-pressure side of the refrigerant circuit through the discharge port.

The refrigerant does not circulate around the refrigerant circuit immediately after the swash-plate-type variable displacement compressor 100 is activated, and thus, the pressure in the suction chamber 192 is equal to or lower than the lower limit value. In this case, the control mechanism 500 opens the low-pressure passage 510 to bring the suction chamber 192 into communication with the pressure adjustment chamber 196. When the suction chamber 192 communicates with the pressure adjustment chamber 196, the inner space of the actuator 400 communicates with the suction chamber 192 through the shaft hole 200A of the drive shaft 200, the through hole 176 of the cylinder block 170, the through hole 180C of the valve unit 180, the pressure adjustment chamber 196 and the low-pressure passage 510. When the inner space of the actuator 400 communicates with the suction chamber 192, the gaseous refrigerant existing in the inner space is introduced to the suction chamber 192, and the pressure is lowered. When the pressure in the inner space of the actuator 400 is lowered, the force pressing the bottomed cylindrical member 420 in the direction which is away from the lug plate 250 is reduced, and when the pressing force becomes smaller than the compressive force of the pistons 450, as illustrated in FIG. 3, the bottomed cylindrical member 420 resists the biasing force of the coil spring 430 and moves in the direction of the lug plate 250.

When the bottomed cylindrical member 420 moves in the direction of the lug plate 250, the inclination angle of the swash plate 300 becomes large by the function of the link mechanism 350. When the inclination angle of the swash plate 300 becomes large, the strokes of the pistons 450 are increased, and the pressure of the gaseous refrigerant discharged from the compression chamber 178 to the discharge chamber 194 becomes high. In this case, since the pressure of the gaseous refrigerant supplied to the high-pressure side of the refrigerant circuit becomes high, the pressure of the gaseous refrigerant supplied from the low-pressure side of the refrigerant circuit to the swash-plate-type variable displacement compressor 100 rises, and the pressure in the suction chamber 192 also rises. When the pressure in the suction chamber 192 rises, the control mechanism 500 gradually reduces the opening degree of the low-pressure passage 510 to bring the discharge chamber 194 into communication with the pressure adjustment chamber 196. Then, the gaseous refrigerant of the discharge chamber 194 in which the pressure rises is supplied to the inner space of the actuator 400 through the high-pressure passage 520, the pressure adjustment chamber 196, the through hole 180C of the valve unit 180, the through hole 176 of the cylinder block 170 and the shaft hole 200A of the drive shaft 200.

The gaseous refrigerant supplied to the inner space of the actuator 400 resists the biasing force of the coil spring 430 and the compressive force of the pistons 450, and as illustrated in FIG. 4, moves the bottomed cylindrical member 420 in the direction which is away from the lug plate 250. When the bottomed cylindrical member 420 moves in the direction which is away from the lug plate 250, the shoulder portion of the bottomed cylindrical member 420 presses the swash plate 300, and the inclination angle of the swash plate 300 with respect to the drive shaft 200 is gradually reduced by the function of the link mechanism 350. When the strokes of the pistons 450 are decreased due to decrease in the inclination angle of the swash plate 300 and the pressure in the discharge chamber 194 is lowered, the pressure of the gaseous refrigerant supplied to the high-pressure side of the refrigerant circuit is lowered. Then, the pressure of the gaseous refrigerant supplied from the low-pressure side of the refrigerant circuit is lowered, and the pressure in the suction chamber 192 is lowered. When the pressure in the suction chamber 192 is lowered, as described above, the pressure in the inner space of the actuator 400 is lowered, and the inclination angle of the swash plate 300 is increased.

Therefore, the pressure of the gaseous refrigerant supplied from swash-plate-type variable displacement compressor 100 to the high-pressure side of the refrigerant circuit can be adjusted to a predetermined pressure by appropriately setting the operating characteristics of the control valve 530 and orifice 540 in the control mechanism 500.

When the rotation of the drive shaft 200 is stopped, the compressive force acting on the bottomed cylindrical member 420 of the actuator 400 from the pistons 450 through the swash plate 300 disappears, and thus, the coil spring 430 which is arranged in the inner space of the actuator 400 moves the bottomed cylindrical member 420 in the direction which is away from the lug plate 250. Accordingly, as illustrated in FIGS. 1 and 4, the inclination angle of the swash plate 300 with respect to the drive shaft 200 is reduced, and thus, the start-up torque of the swash-plate-type variable displacement compressor 100 can be reduced.

Additionally, since the bottomed cylindrical member 420 of the actuator 400 has a smaller diameter portion 420B of the cylindrical shape extending along the drive shaft 200, the inclination of the bottomed cylindrical member 420 with respect to the drive shaft 200 becomes less, so that it can be moved smoothly. Furthermore, since the cylindrical member 410 of the actuator 400 is in the simple cylindrical shape which is separate from the lug plate 250, this can be easily manufactured. In addition, since the cylindrical member 410 and bottomed cylindrical member 420 of the actuator 400 are arranged concentrically with the drive shaft 200, even if, for example, the cylindrical member 410 and bottomed cylindrical member 420 are integrally rotated with the drive shaft 200 by friction, the vibration caused by the eccentricity of the center of gravity can be suppressed.

The embodiment for implementing the present invention has been described; however, the present invention is not limited to this embodiment, and can be variously modified and altered based on the technical idea of the present invention, as an example is provided below.

In order to improve the air tightness between the cylindrical member 410 and the bottomed cylindrical member 420 in the actuator 400, as illustrated in FIG. 5, a seal member 620 such as O-rings, for example, can be arranged between the outer peripheral surface of the cylindrical member 410 and the inner peripheral surface of the bottomed cylindrical member 420. Additionally, in order to improve the air tightness between the bottomed cylindrical member 420 and the drive shaft 200, a seal member 630 such as O-rings, for example, can be arranged between the inner peripheral surface of the smaller diameter portion 420B of the bottomed cylindrical member 420 and the outer peripheral surface of the drive shaft 200.

The bottomed cylindrical member 420 of the actuator 400 can also be the simple bottomed cylindrical shape which does not have the smaller diameter portion 420B, as illustrated in FIG. 6, if the inclination with respect to the drive shaft 200 is unlikely to be a problem. In this case, in order to improve the air tightness between the bottomed cylindrical member 420 and the drive shaft 200, as illustrated in FIG. 7, a seal member 640 such as O-rings, for example, can be arranged between the inner peripheral surface of the through hole 420A of the bottomed cylindrical member 420 and the outer peripheral surface of the drive shaft 200.

REFERENCE SYMBOL LIST

-   100 Swash-plate-type variable displacement compressor -   200 Drive shaft -   250 Lug plate -   300 Swash plate -   350 Link mechanism (coupling mechanism) -   400 Actuator -   410 Cylindrical member -   420 Bottomed cylindrical member -   420B Smaller diameter portion -   430 Coil spring (biasing member) -   620 Seal member -   630 Seal member -   640 Seal member 

1. A swash-plate-type variable displacement compressor comprising: a rotationally-driven drive shaft; a lug plate integrally fixed to the drive shaft; a swash plate fixed in a manner capable of being variably inclined to the drive shaft; a coupling mechanism for coupling the lug plate and the swash plate while permitting variable inclination of the swash plate, and an actuator which is arranged between the lug plate and the swash plate and which uses pressure to change an inclination angle of the swash plate, wherein the actuator comprises: a cylindrical member which extends from a surface of the lug plate toward the swash plate, a bottomed cylindrical member fitted capable of being relatively displaceable to an outer peripheral surface of the cylindrical member, and a biasing member which is arranged in an inner space defined by the lug plate, the cylindrical member and the bottomed cylindrical member, and which biases the bottomed cylindrical member in a direction which is away from the lug plate.
 2. The swash-plate-type variable displacement compressor according to claim 1, wherein the bottomed cylindrical member has a smaller diameter portion fitted capable of being relatively displaceable with respect to an outer peripheral surface of the drive shaft.
 3. The swash-plate-type variable displacement compressor according claim 1, wherein the cylindrical member is separate from the lug plate.
 4. The swash-plate-type variable displacement compressor according to claim 1, wherein a seal member for securing air-tightness with the drive shaft is attached to the bottomed cylindrical member.
 5. The swash-plate-type variable displacement compressor according to claim 1, wherein the cylindrical member and the bottomed cylindrical member are arranged concentrically with the drive shaft.
 6. The swash-plate-type variable displacement compressor according to claim 1, wherein the biasing member is a coil spring.
 7. The swash-plate-type variable displacement compressor according claim 2, wherein the cylindrical member is separate from the lug plate.
 8. The swash-plate-type variable displacement compressor according to claim 2, wherein a seal member for securing air-tightness with the drive shaft is attached to the bottomed cylindrical member.
 9. The swash-plate-type variable displacement compressor according to claim 3, wherein a seal member for securing air-tightness with the drive shaft is attached to the bottomed cylindrical member.
 10. The swash-plate-type variable displacement compressor according to claim 2, wherein the cylindrical member and the bottomed cylindrical member are arranged concentrically with the drive shaft.
 11. The swash-plate-type variable displacement compressor according to claim 3, wherein the cylindrical member and the bottomed cylindrical member are arranged concentrically with the drive shaft.
 12. The swash-plate-type variable displacement compressor according to claim 4, wherein the cylindrical member and the bottomed cylindrical member are arranged concentrically with the drive shaft.
 13. The swash-plate-type variable displacement compressor according to claim 2, wherein the biasing member is a coil spring.
 14. The swash-plate-type variable displacement compressor according to claim 3, wherein the biasing member is a coil spring.
 15. The swash-plate-type variable displacement compressor according to claim 4, wherein the biasing member is a coil spring.
 16. The swash-plate-type variable displacement compressor according to claim 5, wherein the biasing member is a coil spring. 